The Cost of Heating
You are living in the 1800’s, which means no furnace or electric, and you are child of a pioneer who has just settled land in the desert plains, meaning no wood to burn. Your house is one small room. The “local” general store, which about 15 miles away, sells, candles (paraffin wax). They each weigh 30.00 grams and cost $0.05 per candle. Your father who is a hard working man but has not been educated and thinks you are the greatest thing since sliced bread, wants to know if you are able to find out how many candles that he should buy in one week in order to not have to make more than one trip to the store a week. Since your previous home had a well establish community and an affluent school system you have the knowledge to complete this task since. Right before you settled here, you just completed your last chemistry lesson; discussing specific heat, unit conversions, calorimeter and exothermic reactions.
You will need to find out the amount of Energy ( in Joules) per gram that the sample candle puts out and then you can calculate how much energy it takes to heat your humble abode from 55° F to 65° F. Your house dimensions are 12ft long x 24ft wide x 8ft high.
The tools at your disposal including the following:
1.Analytical scale- a very accurate digital weight scale. Since were pretending, let’s say it does not read digitally but rather like an old analog (mechanical) weight scale. 2.A small sample candle 3.A aluminum can with 4.Some high quality H2O 5.A measuring cylinder 6.A isolation stand 7.A Digital thermometer- Remember were pretending so pretend it’s an old style mercury thermometer.
Remember, when you heat up the water you are also heating up the aluminum can.
Lab Report Requirements
Your lab write up should include a brief description of the actual procedure you use in order to calculate the energy released by the candle (in Joules per gram), data tables, sample calculations, and what mass of candle needs to be burned to heat up the house from from 55 deg Fahrenheit to 65 deg Fahrenheit..
Prelab Questions (5 points)
Keep a record of the data in these questions as you will need them for doing calculations (you are turning in the pre-lab remember)
1.Find the specific heat of air, aluminum, and water.
2.Calculate the density of air at 55° F at 710 torr assuming air is composed 80% Nitrogen gas and 20% Oxygen gas.
3. The enthalpy of the combustion of 1 mole of methane is ___ J. What mass of methane must be burned to heat up the room described in the scenerio.
~MEO (with many thanks to Trever Hassell for the story line) 03.31.04 07:56